Unique records (1 Viewer)

[kdt]

Hi

I have a field in a subform that contains a primary key. When entering duplicate value, I want to be able to display a custom message and display the original entry value. So far I've modified some code from msdn to get the following

Private Sub Form_Error(DataErr As Integer, Response As Integer)
   Dim str As String
    Dim ID As String
    Dim rs As DAO.Recordset
    
  'MsgBox "DataErr: " & DataErr
  
  If DataErr = 3022 Then
    'Duplicate record:
    
    ID = CStr(Study_Number.Value)
    
    
    str = "It appears that EmployeeID " & ID _
      & "already exists in the table." & vbCrLf & vbCrLf _
      & "Would you like to view the existing record?"
      
    If MsgBox(str, vbYesNo) = vbYes Then
        Me.Undo 'Undo changes
        Set rs = Me.RecordsetClone
        rs.FindFirst ("Study_Number" = ID)
        Me.Bookmark = rs.Bookmark
    End If
    
  
  End If
  
  'Continue without displaying
  'default error message:
  Response = acDataErrContinue
End Sub

This works fine on a single form, but how can I change it to work to bring both the mainform and subform which is linked master/child.

Any help would be appreciated.

Thanks